Dynamics Of Microglia Activation In Response To Pseudorabies Virus Infection

Aujeszky’s disease was originally found in the United States, scattered over the world from 1920 to1940. For 30 years thereafter, it explosively spread with a significant increase of incidence. At present,the Aujeszky’s is still one of the important diseases that threaten China’s pig industry.Pseudorabies Virus(PRV), subordinate to herpes Virus, is a kind of double-stranded DNA viruswith capsu Le membrane. Animals infected by PRV can replicate itself to move along peripheral nervousnear the infected area, gradually penetrate into the central nervous system(CNS), finally lead to brainlesions. Research the dynamic change of microglia induced by PRV and the dynamic change ofmicroglia have a significant impact on disease development. To do this research, the model ofartificially infecting mouse with PRV was used. Mice inocu Lated with PRV- Bartha K61 vaccine strainincluding three groups of dose, 6×104 TCID50, 1×105 TCID50 and 2.7×105 TCID50 were prepared forexperiment. Three groups of dose all killed the mice after 6 days. The survival rates were 93%, 93% and85%, respectively. However, after 7 days, the survival rates were significantly different that the group of6×104 TCID50 dose kept the same while the other two groups declined to 67% and 14% respectively.The resu Lts showed that all groups resu Lt in brain and brain stem lesions of mice and the lesion levelvaried positively with dose. Thereinto, 1×105 TCID50 dose both caused high survival rate of mice anddamage to brain tissue. So this group was adopted for subsequent test. The dynamical changes ofmicroglia induced by PRV infection was analyzed through immunohistochemical staining, Laserscanning confocal and the flow cytometry. And the proliferating microglia were marked by PCNA andIab1. Iab1 was also used to observe cell morphology of microglia. The results showed that proliferatingmicroglia appeared in brain tissue after infection by PRV,and its morphology turned into activated fromresting. Microglia was proved to be not proliferated in situ via Brd U tracing technique. Moreover, flowcytometric analysis with different phenotypic markers in cells gated for CD11 b expression microgliashowed that proliferating cells were CD11b+CD45hi Gr1+Ly6G-Ly6 Chi, meaning its origin was peripheralinflammatory monocytes. Classically activated macrophage(M1 type) markers, such as i NOS, TNF-α,IL-6 and IL-12 increased with time course by Semi-quantitative PCR technique. However, theexpression of alternatively activated macrophage(M2 type) markers, IL-10 and YM1 also increased at 6and 7 d after infection by PRV. The results showed that microglia were induced into M1 and M2 afterinfection of PRV. The involvement of microglial activation in pathogenicity of PRV needs to be furtherstudied.